| Shortages of water resources is an important factor limiting crop production in semi-arid areas of the Loess Plateau.Film mulching changes the basic physicochemical characteristics of soil through its effects on soil temperature and moisture,and is one of the effective methods to improve soil moisture conditions and maintain high and stable crop yields in dry farming areas.In order to explore the effects of different mulching methods on soil structure,nutrient characteristics and maize yield in dry crop farmland,in this study,we compared the effects of common mulching methods : full film mulching on double ridges(D),flat planting with half film mulching(F),film mulching on ridges and planting in wide furrows(R)on soil aggregates,organic carbon content and their components in dry crop farmland from the perspective of soil structure,using traditional fat planting without mulching(CK)as control,and to analyze the characteristics of soil aggregates distribution and organic carbon content in dry crop maize fields under different mulching methods,combined with soil moisture and maize yield,analyzed and screened suitable mulching patterns in dry crop areas,and provided theoretical basis for perfecting sustainable and stable high-yielding cropping patterns in dry crop fields.The main results of this study are as follows:(1)Compared with CK,different mulching treatments significantly increased soil water storage,with an average increase of 3.42%(R),9.50%(F)and 10.82%(D)in 2020 and 3.14%(R),8.11%(F)and 8.88%(D)in 2021,respectively.The water consumption of all mulching treatments was significantly higher than that of traditional fat planting without mulching CK,showing a trend of F>R>D>CK,while there was no significant difference between mulching treatments F and R.(2)The particle size distribution of soil mechanical stability aggregates was basically the same among different mulching treatments,mainly concentrated in 3 particle sizes >2 mm,<0.25 mm and 1-0.25 mm,with the highest content of >2 mm particle size aggregates and the lowest content of 2-1 mm particle size aggregates,showing an overall pattern of D>R>F>CK.mulching significantly improved the size and stability of soil water stability aggregates.The mulch significantly increased the size and stability of soil water-stable aggregates,and the content of water-stable aggregates increased with decreasing grain size in all treatments,with the highest content of microaggregates(<0.25 mm)and the lowest content of large aggregates(2-1 mm).As the soil layer deepened,the content of >0.25 mm aggregates tended to increase with different mulching methods,and the soil had the highest content of large aggregates(>0.25 mm)and the most stable aggregate structure in the 40-60 cm soil layer.Compared with CK,the mean weight diameter(MWD)of soil water-stable aggregates increased by an average of 29.77%,21.03% and 14.42%,and the geometric mean diameter(GMD)increased by an average of 18.07%,12.575% and 8.34% in the D,F and R treatments,respectively,over two years.Overall,treatments R and F had the best enhancement effect in the 20-40 cm soil layer,and treatment D had the best enhancement effect in the 0-10 cm soil layer.(3)Each mulching treatment increased soil organic carbon content in all soil layers from0-60 cm,with the largest increase in full film mulching on double ridges(D),and the size of each treatment was D>R>F>CK,and the increase gradually decreased with the deepening of the soil layer.In the two-year experiment,soil organic carbon in the whole soil layer from 0-60 cm was significantly(P<0.05)higher in treatment D than in R,F and CK,with an average increase of 7.79%,4.41% and 10.58%,respectively.Soil dissolved organic carbon(DOC),microbial biomass carbon(MBC)and particulate organic carbon(POC)contents of corn gradually decreased with deepening of soil layer after harvest,and all mulching treatments significantly reduced DOC,MBC and POC contents compared to CK.All mulching treatments significantly increased the organic carbon content of soil water-stable aggregates at all grain levels,with D,R and F increasing by 9.68%,12.94% and 9.82%,respectively,on average compared to CK.The organic carbon content of soil aggregates at all grain levels was highest in the D treatment,followed by the R and F treatments among all mulching treatments in the0-60 cm soil layer.(4)Compared to CK,each mulching treatment significantly increased maize yield in both trials,with each mulching treatment R,F and D significant increase by 85.32%,61.32% and93.22%,respectively,in 2020 and 80.68%,55.01% and 101.33%,respectively,in 2021 compared to CK.The R,F and D treatments improved water use efficiency by 75.15%,35.64%and 91.30%,respectively,compared to CK,with the D treatment having the highest water use efficiency in both trials.The water use efficiency was highest in D treatment followed by R treatment in both experimental years.Although mulching increased the total input,it significantly increased the total yield by increasing maize yield and improved farmers’ profitability,and the net yield performance of each treatment was D>R>F>CK.In summary,mulching improved soil moisture,soil aggregate structure and soil organic carbon content in dry farmland,and improved spring maize yield and economic efficiency.Among them,the effect of full film mulching on double ridges was the most significant,which could improve soil aggregate structure,soil water use efficiency and soil organic carbon content on the basis of stable and high yield,and helping to promote sustainable agricultural development in arid areas. |
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